Excitation circuits for reversibly powered translating devices



July 1, 1958 Filed Nov. 26, 1954 TRANSLA'I ING DEVICES 2 Sheets-Sheet 1 July 1 1958 PELL 2,841,756

E. EXCITATION CIRCUITS FOR REVERSIBLY POWERED TRANSLATING DEVICES 2 Sheets-Sheet 2 Filed Nov. 26, 1954 EXCITA HQEN PGWERE TRANSLAi-HNG DEVECES Eric Fell, Wauwatosa, l

-s., assignor to Cu Inc., Milwaukee,

Wis, corporation oi Application November 26, ififid, Serial No. iiiflifi 4 Claims. 322- 7'7) This invention relates to improved excitation circuits for inductive energizing windings of reversibly powered translating devices.

Because of the unidirectional character of re output of electronic and magnetic amplifiers their application to control-of appreciable amount of reversible power to the fields of exciters, generators and motors is somewhat limited. While several. push-pull circuits for amplifiers have been devised to enable their supplying reversible power to the fields of such dynamo electric machines, the required power output ratin of the amplifiers must be considerably in excess of the power actually consumed by the fields of these machines. The ratio of the required power output of the amplifiers to that consumed by the field windings has been in some cases on the order of 12 to 1 and on the order of 8 to l in the best circuits hereto fore devised.

It is a primary object of the present invention to provide improved excitation circuits for the inductive cnergizing windings of translating devices, such as the field windings of dynamo-electric machines, requi ng that the power output ratings of the amplifiers or other sources of regulable unidirectional voltage output be only on the order of four times that actually consumed in the windings.

Other objects and advantages of the invention will hereinafter appear.

The accompanying drawings illustrate preferred embodiments of the invention that will now be described in detail, it being understood that the embodiments illustrated are susceptible of modification without departing from the scope of the appended claims.

In the drawings:

Figure l is a diagrammatic showing of a dynamo electric machine and an improved excitation circuit for field windings of such machine incorporating the invention.

Fig. 2 is a diagrammatic view of a modified form of the invention.

Fig. 3 is like Fig. 2, but shows another modified form of the invention.

Fig. 4 shows a third modified form of the invention, and

Fig. 5 shows a fourth modified form of the invention.

In Fig. 1, DM generally designates a D. C. dynamo electric machine having an armature A and field windings f1 and f2. It may be assumed that these field winding sections are wound together in parallel and together provide the same number of turns as a single field winding. Winding section fl is connected at one end to output terminal lltl of a magnetic ampliner ii, and winding section f2 is connected at its corresponding end in series with a resistor 13 to output terminal lid. At its other end winding fl is connected to output terminal 14 of a magnetic amplifier l5, and winding f2 is connected at its other end in series with a resistor 16 to output terminal 14. The juction between resistor 13 and winding f2 is connected to the other output terminal 17 of amplifier l5, and the junction between winding f2, and resistor 16 is connected to the other output terminal it; of amplifier ll. Re-

2% sisters 13% and is are each preferably equal in ohmic value to that of field 'ndings fl and '12.

Amplifier ill is supplied with A. C. power from a transformer l and amplifier 15 is similarly supplied from a transformer Secondary winding 19 of transformer 153 is connected at one end in series with a half-wave rectifier to output terminal in, and output terminal 13 is o .ected the same end of winding 19* in series with a hali wave rectifier Z2. Winding is connected at its JL) other end in series with an C. main winding 23 and half-wave rectifiers 2d and to output terminal 10. Output terminal 18 is connected in series with half-wave rectifiers 26 and 237 and A. C. main winding 28 to said other end of Winding l9 The points common between rectifiers 2e and 27 is conected by a conductor 29 to the point common between rectifiers and 25. Secondary winding ,d oi transformer Ed is connected to output terminals 17 of amplifier in a corresponding manner and the various A. C. main windings, rectifiers, etc., have been given identical reference numerals.

Amplifiers ill and 15 are provided with D. C. bias windings and 31, respectively, which are connected across lines Li and L2 of a source of C. voltage in series with an adjustable resistor 32 These amplifiers are also provided with D. C. control wi lugs 33 and 34, respectively, which are connected at ad acent ends. At its other end, winding is connected to the left-hand contact of stationary contacts 3" and the right-hand contacts of stationary contacts a polo, double throw switch 35. The other end of winding 34 is connected to the right-hand contact of contacts 35 and to the lefthand contact of contac Switch 35 has movable contactors 35 which are connected across lines Li. and L2 in series wi an adjustable resistor Amplifiers ill have cut-oft points in accordance with the a J U... of resistor s2. With contactors 35 closed to contact of switch 35, it may be assumed that winding I will be directionally energized to turn amplifier l on to degree determined by the adjustment of resistor it may also be assumed that will be directionally energized so that ampliwinding fier will be turned full-oft. With COIJMCiUlS 35 closed to contacts 3:3, it may assumed that amplifier i5 is turned on and amplifi will be turned full-off.

As will be under od, where it is desired to control the output of amplifiers and i5 response to a signal variable in accordance with changes in load or other conditions imposed on machine DM, such amplifiers would each be provided with signal control windings which would provide ampere urns acting difierentially with respect to the ampere turns provided by the windings 33 and 3d thereof, to vary the output of such amplifiers. Such v dings have been itted from the disclosure of Fig. l for the sake of simplicity.

if amplifier ii is 1 -ed on and anu full-oil, current will fiow from output terminal it] of amplifier ill through field winding fl and resistor 16 to output terminal 318, and similarly current will fiow from output terminal in through resistor l3 and field winding f2 to output terminal 13. Conversely, if amplifier 15 is turned on and amplifier ll is turned full-oil, current will fiow from output terminal 14 through field winding fl and through resistor 13 to output terminal 5.7, and similarly current will fiow fr output terminal 14 through resistor 16 and u 4 a to output terminal 17. Reversal of the direc of current ilow through field windings f 'se cause reversa I, it it be a mo versal in polarity of its armature voltage if it be a generator or eXciter.

Even though field windings resistors and 1d are of equal to .n'ier turned and f2 are alike and each in ohmic value,

pensed with.

not all of the current flowing between the output terminals of a turned-on amplifier will fiow through the field windings f1 and f2. Due to the fact that the current output of the amplifier is not pure D. C., but is of pulsating character, some of the current will by-pass field windings f1 and f2 and flow through either resistor 13 or 16, and the rectifiers of the turned-off amplifier back to the return output terminal of the turned-on amplifier. in order to improve the eficiency of the circuit, the system depicted in Fig. 2 has been devised, wherein filter circuits, comprising a capacitor 37 and adjustable resistor 38 are connected in series across the output terminals of each of the amplifiers 11 and 15. These'filter circuits help to provide output current that more closely approaches pure D. C. 'in form, and hence causes less of the output current of a turned-on amplifier to be by-passed around field winding sections fl and f2 through the rectifiers of the turnedoff amplifier.

Fig. 3 depicts another modified form for improving the efficiency of current flow through windings fl and f2. In this form center-tapped resistors 39 and 4d are substituted for resistors 13 and 16, respectively, and a discharge resistor 41 is connected across the center taps of resistors 39 and 40. The current supplied by the turned on amplifier will, because of the inductance of the field windings, find it easier on the increase slope of the rectified current Wave to pass through the rectifiers of the turned-oil amplifiers, but on the decaying side or slope of the current wave the energy built-up in the field windings cannot pass through the last mentioned rectifiers. Thus the resistor 41 provides a discharge path for both of the field windings and improves the amplifier output current flow through these windings.

The modified form of Fig. 5 is like the form of Fig. 3 except for the additional inclusion of a switch 45 in the connection between output terminal w of amplifier ii and the junction between field winding f1 and resistor 39, and the similar inclusion of a switch 56 in the connection between output terminal 14 and the junction between field winding fl and resistor 4%. It is contemplated that with amplifier 11 turned on and amplifier 15 turned off switch 45 will be closed and switch 46 will be opened, thus preventing the short circuiting of current through the rectifiers of amplifier 15. Similarly with amplifier 1" turned on and amplifier ll turned-0E switch 46 will be closed and switch 45 will be opened preventing the short circuiting of current through the rectifiers of amplifier 11. During quick reversing or plugging operation, with the previously turned-0E amplifier suddenly turned on and the previously turned-on amplifier suddenly turned oil, discharge resistor 4-1 provides a discharge path for the stored magnetic energy of windings fl and f2. For slow reversing applications, discharge resistor 41 can be dis- In the modified form of Fig. 4, the center taps of resistors 39 and 4d are interconnected through a switch 59 and half-wave rectifier 51 connected in series with switch 50 and also through a switch 52 and a half-wave rectifier 53 connected in series with switch 52. Rectifiers 51 and 53 are connected in the opposed conducting relation shown. With amplifier 11 turned on and amplifier 15 turned ofi switch 59 would be closed and switch 52 opened thereby insuring that more current will flow through windings f1 and f2. Conversely with amplifier TSturned on and amplifier ll turned off switch 52 will be closed and switch 5% opened to secure similar increased current fiow through windings f1 andfZ in the reverse direction. Under steady state conditions this form shows higher efficiency than either of the forms of Figs. 3 and 5 as it eliminates current drain through a discharge resistor.

Any of the aforedescribed forms can be improved upon from a current distribution standpoint by substituting inductors for the resistors connected between the ends of the field windings, such inductors preferably having the same inductive reactance and ohmic resistance as windings fl and f2. Electronic amplifiers can also be used in place of the magnetic amplifiers here disclosed, and the.

windings f1 and f2 can be inductive control or regulating windingsof translating devices other than dynamo electric machines.

I claim:

1. In combination, a translating device having a pair of inductive regulating windings, a pair of center tap re-.

sistors connected in a bridge circuit with said windings and disposed in alternate legs thereof, two parallel series groups, each comprising a switch and a half-wave rectifier connected between the center taps of said resistors with the rectifiers connected in opposed conducting relation with res ect to the other, and a pair of unidirectional voltage sources, one of which has its output connected across one pair of diagonally opposite junctions of said bridge circuit and the other of which has its .outputconnected across the other pair of diagonally opposite junctions of said bridge circuit.

2. In combination, a dynamoelectric machine having a pair of shunt field windings, a pair of center tap resistors connected in a bridge circuit with said fieldwindings and disposed in said alternate legs thereof an impedance element connected between the center taps of said resistors, and a pair of amplifiers of the unidirectional output type, one of which has its output terminals connected across one pair of diagonally opposite junctions, of said bridge circuit and the other of which has its output terminals connected across the other pair of diagonally opposite junctions of said bridge circuit.

3. The combination according to claim 2 wherein said impedance element is a resistor. 7

. 4. A combination according to claim 3 wherein a switch is in the connections between the output terminals of each said amplifiers and said bridge circuit.

References Cited in the file of this patent UNITED STATES PATENTS 

